Functional traits predict herbaceous responses to land-use intensities in the grassy biomes of South Africa

Authors:
Stefan Siebert

Publication Date:
2019

Abstract/Summary:
Disturbance alters the taxonomic and functional composition of vegetation. In disturbed ecosystems, plant fitness (i.e. survival, growth and reproduction) is dependent on local environmental conditions such as climate, fire, and herbivory. Interconnected effects of land-use intensity and local environmental stressors on herbaceous vegetation resistance and resilience are poorly understood in the grassy biomes of South Africa. A functional-trait approach was used to define traits related to vegetation resistance and resilience across three disturbance gradients in grasslands and savannas. At each grassland and savanna site, areas of cultivation, urban open space and mining sites were sampled, all of which covered three land-use intensities (i.e. old growth, hybrid, and novel ecosystems). Measures of functional trait loss were used to evaluate vegetation resistance and resilience to land-use intensity combined with local environmental stressors. Compared to the more resilient grassy savanna ecosystem, the grassland sites showed considerable losses in the functional trait pool, especially from the hybrid to the novel ecosystem state. Both biomes are seasonal, fire-driven grassy ecosystems and yet they respond invariably to land-use intensification. Functional traits in the grasslands are mostly related to below-ground storage organs to survive natural disturbances, including frost. This trait pool may persist in hybrid states but disappears with land-use intensification related to soil disturbance. Savannas host a much larger trait pool, which buffers the system against both anthropogenic and natural disturbances. Delineating the functional traits related to plant fitness should allow for meaningful contributions to restoration efforts, provided that local environmental adaptations are considered.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Pre-approved for CECs under SER's CERP program

Source:
Society for Ecological Restoration